What is an Expander?

What is an Expander?

Expanders increase the difference in loudness between quieter and louder sections of audio making quiet sounds quieter and loud sounds louder.  They are pretty much the opposite of compressors working by turning down the volume when the signal level falls below the threshold and turning the volume back up when the signal level goes above the threshold.

Expanding is useful when you want to increase the dynamic range of the audio. For example, when you have a noisy recording and want to reduce the volume of the quieter parts so you don’t notice the noise as much.   A side effect of expanders is that they change the way sounds decay and can end up silencing quieter parts of your audio that you want to keep.

The main controls on an expander are: attack and release times, and ratio.

The attack time sets how fast the expander responds to signal levels above the threshold.

The release time sets how fast it reacts when the signal level drops below the threshold.

The ratio determines how much to turn the volume down. A higher ratio results in the volume being turned down more. A very high ratio of 12:1 or more is considered a noise gate.